This invention relates to a beam picker and more particularly to a device which is designed to be used in conjunction with a conventional hydraulic crane to enable shoring beams to be removed from beneath bridges or the like after the bridges have been completed.
When modern post tension bridges are constructed, the forms and concrete mass are normally supported by falsework towers and temporary structural beams or shoring beams. In such a structure, the concrete is poured in place and supported by falsework until after the bridge is post tensioned with high strength cable strands.
In the typical construction of such a bridge, the towers and the grid of supporting steel beams which support the wood or metal forms are easily put into place using conventional construction cranes. The bridge constructed in this manner is usually positioned over another roadway such as used in the interstate exchanges involving off ramps, on ramps, cloverleafs, etc. Thus, in this type of construction, the bridges are built on land which allows support towers to be placed at frequent intervals to support the extreme weight of the bridge during the construction phase and prior to post tensioning. In such a construction operation, there is usually no overhead obstruction for the bridge. Conventional cranes can swing and set the towers and the support beams using conventional rigging methods. The load is normally supported by hoist lines extending from cranes and rigging cables.
However, after the bridge is poured and post tensioned, it is necessary to remove the support steel and the towers supporting the same from beneath the new structure. Such a removal operation has troubled the industry and methods to overcome the same have only been partly successful. In the past, some of the beams have been removed by the "crash method". This method amounts to typing a cable to the beam to be removed and utilizing a large piece of equipment to physically drag the beam off the supporting towers and let it crash to the ground. This method is extremely damaging to the beams or anything the beams might hit on their drop to the ground. Such a method is also dangerous to workers in the area not only from the falling beam but from boards and lumber hit by the beam which may fly in unknown and unpredictable directions.
In certain instances, the entire section of the falsework may be lowered by winches. While the winch method may be a good method, it is not always possible or desirable to use this method. Even if the steel grid is lowered in large sections by winches, it is still necessary to remove the shoring support towers prior to the lowering operation. This necessitates removal of the towers by some means prior to the lowering of the steel grid.
It is therefore a principal object of the invention to provide a beam picker which may be attached to the boom tip of a conventional hydraulic crane.
Yet another object of the invention is to provide a beam picker which includes means for clamping onto the beam to be removed, tilting the beam and rotating the beam.
A further object of the invention is to provide a beam picker adapted to be mounted on the boom tip of a hydraulic crane which may be easily installed on the crane or removed therefrom.
Yet another object of the invention is to provide a beam picker of the type described which may be positioned beneath most structures by the hydraulic crane, grasp a beam by clamping the bottom flange thereof and removing the beam with the apparatus having the ability to tilt the beam, move the beam laterally, or rotate the beam.
Still another object of the invention is to provide a device of the type described which is safe to use.
These and other objects will be apparent to those skilled in the art.